Scanner with light directing channel

ABSTRACT

A light diverting channel for use in a scanner. The channel is incorporated into the cover of a flat bed scanner and transmits light from the lamps positioned longitudinally along the scanner, up through the side of the channel, and through a central region or sheet of the channel, and then down through objects to be scanned. The light diverting channel thereby more efficiently uses the light generated by the lamps and more evenly disburses the light over and through the object to be scanned.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to optical scanners and, moreparticularly, to a scanner mechanism adapted for transmissive scanningand having a light transmitting channel to transfer light from the lightsource, typically a fluorescent tube placed along the edge of the platenon either side, of the scanner and to direct that light transmitted upthrough the platen and then over and around the object to be scanned andthen reflected down to thereby provide for enhanced light over theentire area of the scanning platform and through the object to betransmissively scanned.

[0003] 2. Description of the Related Art

[0004] Optical scanners are typically used to electronically reproducevisually perceptible images on materials, such as documents, photographsand transparencies, in a digital format for use by a computer. Onceimages have been stored on a computer, they may be altered andreproduced for any purpose, including the reproduction of highdefinition imaging for use in multimedia-type applications.

[0005] Optical scanners are available in a variety of configurations,tailored to the needs of the user. For example, a conventional flatbedscanner includes a light-receiving device mounted in a light-receivingseat. The seat is coupled to a pair of rails and is movably adjustedalong the rails for scanning line-by-line documents and photographs forreflective scanning, and transparencies for transmissive scanning. Thelight-receiving device includes mirrors and a lens for focusing theimage upon an elector-optical transducer, i.e., a charge coupled device(CCD) which then converts the light images into electrical signals.These signals are then digitized for use by a computer for reproductionand manipulation of the digitized image by commercially availablesoftware. In conventional scanners, the CCD is centrally mounted withinthe light-receiving device. The device may also include the use of afocusing mechanism for adjusting the distance between the lens and theCCD.

[0006] The light source or sources for conventional scanners, inparticular, transmissive scanners, are usually fluorescent tubes placedso that light radiating outward from the tubes is transmitted throughthe transparency, through an optical pathway and eventually to the CCD.One problem with such scanners is associated with the unevendistribution of light from the light source over the entire area to bescanned. For example, the areas of the transparency closest to the lightsource will have greater intensity and the areas of the transparencyfarther away from the light source will have less light intensity.Inasmuch as the intensity of light varies as the inverse of the squareof the distance from the light source, it is apparent that a wide rangeof intensities may result over the entire surface area of thetransparency, depending on its size and distance from the light sourceand whether the scanner includes components to diffuse the light overthe entire surface of the transparency.

OBJECT OF THE INVENTION

[0007] The primary object of the present invention is to provide achannel-shaped light transmission feature for transmissive scanning inan optical scanner, whereby light radiating from a light source istransmitted from a region adjacent to the light source to an area on oneside of the object to be scanned, and is dispersed relatively evenlyover the entire area of the object to be transmissively scanned, wherebymore efficient use of the light emitting from the light source, andenhanced scanning of the object to be scanned results.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to a mechanism and method forscanning transparencies within a conventional scanner adapted fortransmissive scanning and using a conventional CCD-type image processingstructure and capability. The mechanism includes a U-shaped channelwhich is incorporated within the cover or lid of a flatbed scanner andhas its legs extending longitudinally along the outer edges of theplaten of the scanner, and above fluorescent tubes positioned under theplaten and along the longitudinal axis of the flatbed scanner. Theinverted, U-shaped channel includes a reflective layer positionedadjacent the floor of a cavity formed in the scanner lid, a fiber opticlight conduit for transmitting light upward from the legs and throughthe center, or base part of the U-shaped channel, and a collimatinglayer positioned adjacent the conduit layer on one side, and adjacentthe platen of the scanner on the other side, for collimating light whichhas been transmitted through the polymeric conduit and reflected fromthe reflective surface to thereby direct the light through the object tobe scanned and through an optical pathway to the CCD of the scanner.

[0009] The preferred light diverting channel of the present inventionincludes a polymeric conduit to serve as a wave guide, a reflectivesurface, and a collimating layer which includes a sheet havingwedge-shaped collimators on one side and arcuate truncated edged lenseson its opposite side. With incorporation of the light directing channelof the present invention, the transmissive scanning is improved byvirtue of more efficient transfer of light from the light source to andthrough the object to be scanned, and, also, more even distribution oflight over the entire area of the object to be scanned.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The objects and advantages of the present invention will becomemore readily apparent to those of ordinary skilled in the art afterreviewing the following detailed description and accompanying documentswherein:

[0011]FIG. 1 is a perspective view of a preferred embodiment of thepresent invention;

[0012]FIG. 2 is a bottom view of the cover of the FIG. 1 embodiment;

[0013]FIG. 3 is a cross-sectional view of the FIG. 2 cover, taken alongline 3-3;

[0014]FIG. 4 is a cross-sectional view of the FIG. 1 scanner, takenalong line 4-4;

[0015]FIG. 5 is a top, side perspective view of a section of thecollimation sheet used in the preferred embodiment; and

[0016]FIG. 6 is a bottom, side perspective view of the FIG. 5collimation sheet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Referring to the drawings more particularly by reference numbers,FIG. 1 shows a scanner 20 having a conventional housing 22 as used in aflatbed type scanner. The scanner also includes a cover 24, which isconnected to the scanner by any conventional means, preferably by hingeslocated at one end, in a conventional fashion. The scanner also includesa conventional glass platen 26. The top surface of the scanner housingincludes a border 28 which surrounds the rectangular platen 26. Shown indotted lines in FIG. 1 a first light source 30, and a second lightsource 32. Preferably these light sources are conventional, fluorescenttubes which extend longitudinally along the inside of the housing andprovide a light source for illuminating the object to be scanned, whichis placed on the platen 26. The scanner also includes, typically, amovable carriage which reciprocates along a rail or rails orientedlongitudinally along the length of the housing. The carriage typicallyincludes a scanning camera, usually including an elector-optictransducer, for example, a charge coupled device (CCD), focusing and/orcollimating lenses, and one or more mirrors used to define a path oflight through a transparent object, through the lens or lenses to theelector-optical transducer. The cover, or lid 24 is preferably hinged atone end, the hinges being conventional and not shown in FIG. 1.

[0018] With reference to FIGS. 2 and 3, the cover 24, incorporating thelight directing layer will be described. FIG. 2 is a bottom view of thecover or lid 24, with reference to FIG. 1 in which the top of the cover24 is shown. The bottom of the cover 24 includes a first width-wiseborder 26 extending width-wise at a predetermined distance along theentire width of the end of the cover which is not hinged. At the hingedend of the cover another margin or border 28, shown having the samedistance and also extending across the entire width of the cover 24 isshown. Mounting posts 34 and 36 are also shown for mounting the cover tohinges at the hinged end of the lid. Extending along the longitudinaldirection of the cover are borders or margins 30 and 32, each of whichis of a pre-determined width or distance. Inside of the borders ormargins 26, 28, 30 and 32 is positioned a preferred embodiment lightdiverting channel 38 of the present invention.

[0019] Referring to both FIGS. 2 and 3, the light diverting channel 38includes a central, rectangular area or surface 46 which is of apredetermined length and width, chosen to be large enough to overliedocuments or other objects to be scanned. As shown in FIG. 3, incross-section, the light diverting channel 38 has the form of a shallow,U-shaped channel with the distal ends or surfaces of each leg of the Ubeing shown at 40 and 42. The height of the leg 40 is shown at 41 andthe height of the leg 42 is shown at 43. When the cover is oriented sothat it lies flat over the housing 22 of the scanner, the surfaces 40and 42 of the light diverting layer 38 lie flat on the platen 26. Thecavity formed by the platen 26 on the bottom, the central surface 46 ofthe light diverting layer 38 and the legs with the height shown at 41and 43 provide space for the transparency, or other object to bepositioned and permit the edges 40 to 42 to lie flat along the platen 26of the housing. The light diverting channel is fastened within a cavityof the housing 24 by any conventional means such as by press fitting,with an adhesive, or with other conventional fastening means such asscrews, brackets, or any other conventional means, so long as thefastener performs the function of retaining the light diverting channelwithin the cover and so as to permit the light diverting channel toperform its intended function of diverting light upward through the legs40 and 42, across the central region 46, and then down through theobject to be scanned. As is also apparent, the present embodiment isadapted for transmissive scanning, rather than reflective scanning. Inthis mode of operation, typically a transparency, such as a 35 mm slide,or larger transparency is the object to be scanned and the source oflight is oriented so that it transmits light through the object to bescanned. Also shown on FIG. 2 is a rectangular region, or border, 44which extends across the width of the central area 46 of the lightdiverting layer, and extends for a predetermined length, longitudinally,along the length of the cover. This region 44 is a calibration region,and, is preferably, of a white, reflecting surface, and is used for thescanning camera assembly and included software application to properlycalibrate itself for scanning of an object.

[0020] With reference to FIG. 4, the path of light from the light sourceto the scanning camera will be described. FIG. 4 is a cross-sectionalview of the FIG. 1 scanner taken through line 4-4, except that the lid24 is shown as being fully closed in FIG. 4, whereas it is in an openposition in FIG. 1. In FIG. 4 the cover 24 is shown in diagonal lines,and the light diverting channel is shown without lines, as well as thecavity formed above the platen and below the central region 46 of thelight diverting layer 38 to facilitate explanation and understanding ofthe light path. The light sources 30 and 32 provide light radiatingoutward from the tubes, as is conventional. As shown in FIG. 4, twovertical arrows pointing upwards from each light source represent raysof light from the lights 30 and 32 directed upward through the surfaces40 and 42 of the light diverting channel 38. As also representedschematically, the light is then reflected, as shown in FIG. 4 by lightray 33 being reflected to form light ray 35 directed into the body ofthe light diverter or light diverting channel 38.

[0021] As also shown in FIG. 4, light reflecting and transmitted withinthe light diverting channel 38 is reflected off of the reflecting layer37. As represented schematically in FIG. 4, the light is then shownreflected from reflective layer 37 in a downward direction as shown bythe arrows, one of which is numbered 39. The light being thus reflecteddownward passes through the interior layer of the light divertingchannel 38, and through a collimating layer 41, as will be described ingreater detail. The light then passes through the cavity formed by theplaten 26 on the bottom and the light diverting channel 38 at the topand two sides. The cavity for holding the object to be scanned is shownat 43 in FIG. 4.

[0022] The light diverting channel 38 of the present invention isessentially an optical conduit and functions to transmit light from thelight sources 30 and 32 around the edges of the object to be scanned,and then is diffused and evenly spread out and thus to transmit lightover the object to be scanned, as best shown in FIG. 4. The lightdiverting channel 38 must, therefore be made of a material thatfunctions to transmit light. Preferably, the light transmitting channelis made of a three-layer or three-component optical interconnectionwhich includes a reflective layer, a polymeric transmissive layer, and acollimating layer. The most preferred light diverting layer is availablefrom Allied Signal Corporation as corrective optical films which includethree such functional layers. The first layer is the central or lighttransmitting conduit or pipe, which is preferably of a polymericmaterial such as polymethylmethacrylate (PMMA). The PMMA layer is in thecenter, and at one edge a reflective layer is positioned. The reflectivelayer 37, as shown in FIG. 4, is adjacent the surface of the cover whichforms the cavity into which the light diverting channel 38 is placed.The third layer of the light diverting channel 38 is a collimator layer,shown at 41, in FIG. 4.

[0023] The PMMA light conduit, and the reflective layer areconventional. Numerous materials may be used to form an equivalent lightconduit or light pipe and reflective layer, as will be appreciated bythose skilled in this art. The collimator layer, or sheet 41, however,is of, most preferably, a very specific design, as will be shown anddescribed with reference to FIGS. 5 and 6.

[0024]FIG. 5 shows a small portion of the collimation sheet 41 from abottom, side perspective view with reference to FIG. 4. In other words,the light which has been transmitted from the light sources 30 and 32 upthrough the legs 40 and 42 of the light diverting channel 38, andthrough the polymeric light conduit and reflected downward from thelight reflecting layer 37, is shown at arrow 39, and passes through thewedge-shaped collimator elements or lenses one of which is shown at 46,and then outward and downward through the arcuate lenses or lenssegments 48.

[0025] As shown in FIG. 5, the arrow 39 represents the light beingtransmitted through the collimation sheet, and is oriented in adirection opposite that of FIG. 4, for the purpose of betterillustrating the arcuate lens elements 48.

[0026] With reference to FIG. 6, a top view of the same segment 41 ofthe collimating layer is shown, with light being transmitted in thedirection shown at arrow 39 through the wedge-shaped lenses orcollimators 46. The collimation sheet turn includes three layers orsub-layers. The substraight layer 44 is shown as a generally,rectangular sheet having a predetermined thickness. Positioned on oneside of the sheet is a series of wedge-shaped lenses or collimatorelements 46. These wedge-shaped lens or collimators 46 include arelatively broad, rectangular base adjacent the sheet 44, and slopingsides 58 and 60, as shown in FIG. 6, which terminate in a flat,rectangular top 62. As may be appreciated, the area of the top or base62 is smaller than the area of the base or rectangular area which meetswith the sheet 44. On the opposite side or surface of the sheet 44 ispositioned a plurality of arcuate lenses 48. These arcuate lenses havethe appearance of a small segment or sector of a tire, in that they havea central, flat radial band 50 with tapered edges 52 and 54 whichterminate along one edge at the central band 50 and at the opposite endalong an edge 56. As is also apparent from FIGS. 5 and 6, thecollimation lenses 46 and the dispersion lenses 48 are oriented incolumns and rows on opposite sides of the sheet 44, and the centralregions of each row of lenses extending along in one direction isoriented to straddle a line which extends in the same direction andrepresents and defines where each adjacent row of lenses meet. Forexample, as shown in FIG. 6, line 64 having double arrowheads 66 and 68illustrate this orientation. The end of the line 64 at arrowhead 68 isshown in the central, or highest region of a row of arcuate lenses 48.The opposite end of the line 64, shown at arrowhead 66, illustrates andshows the line where collimation wedges 46 meet. The edges 70 and 72 ofthe arcuate lenses 48 are shown in FIG. 6, positioned so that the row oflenses 48 straddles the line 64, and thus the line along which twoadjacent rows of collimation which are positioned.

[0027] During operation, the object to be scanned is placed on theplaten 26, the cover 24 is shut, and the scanner is energized in aconventional fashion. The lights 30 and 32 are energized, and light istransmitted up through the legs 40 and 42 of the light divertingchannel, where it is reflected 900 and transmitted inward toward thecenter region 46 of the light diverting channel. In this region thelight is ultimately reflected from the surface 37, and then downward, asshown in FIG. 4, and upward in FIGS. 5 and 6, through the collimationwedges, the layer 44 and the lenses 48, and then through the object tobe transmissively scanned. As may be appreciated from the abovedescription, a greater amount of light generated by the light sources 30and 32 is transmitted to the object to be scanned, and that light ismore evenly dispersed over the surface area of the object than would bewithout the channel.

[0028] Thus, with the present invention, for a given amount of light,greater efficiency is achieved because a greater amount of light istransmitted to the object to be scanned, and with a given amount oflight transmitted to the object to be scanned, improved scanningresults, because the light is distributed more evenly over the entireobject to be scanned than in conventional designs. Similarly, with useof the present invention, it is envisioned that smaller, and thereforeless costly, light sources may be used to achieve the same degree ofillumination on the surface of the object to be scanned, in comparisonto conventional designs.

[0029] A conventional central processing unit (CPU) (not shown)connected within the scanner controls the movement of the scanner. TheCPU includes a software program which provides the means for the CCD andlens to be correspondingly adjusted in response to selection of adesired scanning mode.

[0030] While the present invention has been described in connection withwhat are presently considered to be the most practical and preferredembodiments, it is to be understood that the invention is not to belimited to the disclosed embodiments, but to the contrary, is intendedto cover various modifications and equivalent arrangements includedwithin the spirit of the invention, which are set forth in the appendedclaims, and which scope is to be accorded the broadest interpretation soas to encompass all such modifications and equivalent structures.

What is claimed is:

1. An optical scanner comprising: a housing containing an electro-optictransducer, a scanning platform adapted to hold objects to be scanned, alight source adapted and positioned to illuminate the object, at leastone mirror adapted to direct illuminance of the object from saidscanning platform onto said electro-optic transducer; a cover having alength, width, thickness and movably attached to said housing; a lighttransmitting channel mounted within said cover; said light transmittingchannel including a reflective layer adapted to reflect light therefrom;a light transmitting layer adapted to transmit light therethrough; and acollimating layer adapted to collimate light passing through saidcollimating layer.
 2. The scanner of claim 1 wherein: the channel isU-shaped; the outer base of the U includes said reflective layer; andthe inner base of the U includes said collimating layer.
 3. The scannerof claim 2 wherein the legs and the central region of the base of thechannel include the light transmitting layer.
 4. The scanner of claim 3wherein said light transmitting layer is made of a polymeric material.5. The scanner of claim 1 wherein the channel legs extend along thelongitudinal axis of the scanner and are positioned at an outerperiphery of said scanning platform.
 6. An optical scanner covercomprising a top surface, a length dimension, a width dimension and athickness dimension; a cavity provided in said cover; a channel-shapedlight directing member positioned within said channel and having itslegs extending along a first direction of said cover.